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Dd October 16, 2016
Dt CND 3
Os
Sh NAME
Nm cnd
Nd condition variable functions
Sh LIBRARY
Lb libpthread
Sh SYNOPSIS
In threads.h
Ft int
Fn cnd_broadcast "cnd_t *cond"
Ft void
Fn cnd_destroy "cnd_t *cond"
Ft int
Fn cnd_init "cnd_t *cond"
Ft int
Fn cnd_signal "cnd_t *cond"
Ft int
Fo cnd_timedwait
Fa "cnd_t * restrict cond"
Fa "mtx_t * restrict mtx"
Fa "const struct timespec * restrict ts"
Fc
Ft int
Fn cnd_wait "cnd_t *cond" "mtx_t *mtx"
Sh DESCRIPTION
The
Fn cnd_broadcast
function unblocks all threads that are blocked on a condition variable
Fa cond
at the time of the call.
If no thread is blocked on the
Fa cond
condition variable at the time of the call,
the function does nothing and returns success.
Pp
The
Fn cnd_destroy
function destroys the
Fa cond
condition variable.
Pp
The
Fn cnd_init
function initializes a new
Fa cond
variable.
Pp
The
Fn cnd_signal
function unblock one thread that currently waits on the
Fa cond
variable.
If there are no threads blocked,
Fn cnd_signal
does nothing and returns success.
Pp
The
Fn cnd_timedwait
function atomically unlocks the mutex
Fa mtx
and blocks on the condition variable
Fa cond
until a thread is signalled by a call to
Fn cnd_signal
or
Fn cnd_broadcast
or timeout
Fa ts
has been reached.
The
Fa ts
parameter is specified as
Dv TIME_UTC
based calendar time.
If the mutex is not locked by the calling thread then behavior is undefined.
Pp
The
Fn cnd_wait
function atomically unlocks the mutex
Fa mtx
and tries to block on the conditional variable
Fa cond
until a thread is signalled by a call to
Fn cnd_signal
or
Fn cnd_broadcast .
The
Fa mtx
mutex is locked again before the function returns.
If the mutex is not locked by the calling thread then behavior is undefined.
Sh RETURN VALUES
The
Fn cnd_broadcast
function returns
Dv thrd_success
on success or
Dv thrd_error
on failure.
Pp
The
Fn cnd_destroy
function returns no value.
Pp
The
Fn cnd_init
function returns
Dv thrd_success
on success or
Dv thrd_error
on failure.
Pp
The
Fn cnd_signal
function returns
Dv thrd_success
on success or
Dv thrd_error
on failure.
Pp
The
Fn cnd_timedwait
function returns
Dv thrd_success
on success, otherwise
Dv thrd_timedout
to indicate that system time has reached or exceeded the time specified in
Dv ts ,
or
Dv thrd_error
on failure.
Pp
The
Fn cnd_wait
function returns
Dv thrd_success
on success or
Dv thrd_error
on failure.
Sh SEE ALSO
Xr pthread_cond 3 ,
Xr threads 3
Sh STANDARDS
The
Nm
interface conforms to
St -isoC-2011 .
Sh HISTORY
This interface first appeared in
Nx 9 .
Sh AUTHORS
An Kamil Rytarowski Aq Mt [email protected]

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